Li, Diyuan; (2021) Developing New Methodologies For Electro-Organic Chemistry. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Electro-Organic Chemistry has great potential to be used extensively in chemical synthesis but remains relatively under-exploited. To help expand this promising field of research, this PhD project was centred around developing new electrochemical methodology for use in organic reactions, particularly through activation of iodide ions and organic iodide compounds. The first research part is related to iodide ions: a dual electrochemical oxidative process in synthesizing the dihydrobenzofuran motif with excellent efficiency has been developed. This allowed for the formation of zinc ions and molecular iodine from a carbon anode in one pot followed by a zinc catalysed iodocyclisation of phenol and alkene. Related mechanistic studies indicate an unusual pathway which explains the selectivity of the reaction without the often-problematic electrophilic aromatic iodination of the aryl ring. Further extension of this newly developed method to aniline has led to a novel aziridine intermediate which ultimately yielded a diaminated product. The second research part is related to the activation of organic iodide compounds. A newly developed electrochemical approach allows the generation of C-centered radicals for radical addition reaction and cyclisation. The yields and efficiency of the processes are superior in most cases to comparable conditions with tributyltin hydride. The use of air and electricity as the promotor combined with the aqueous reaction media make this a clean and ‘green’ alternative to these classic C–C bond forming processes. We have described the reaction mechanism in terms of electrogenerated reactive oxygen species which arises from the reduction of molecular oxygen in the aqueous phase. In addition, for easy and cheap access to this area and enable reactions that require for anhydrous conditions, we have successfully applied a supermarket purchased battery and UV light respectively as replacements of the roles of potentiostat equipment and oxygen in the methodology.

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